HoldsUp

FoundMyFitness · 2025-02-05 · Rhonda Patrick (host), Brady Holmer

How to Train According to the Experts

86 research-tied claims examined: 2 contradicted 5 overstated 6 context 70 supported 3 unverified

70

Supported by research

0:07:44Rhonda Patrick (host)supportedlow

In the 30-year follow-up to the Dallas Bed Rest Study, participants' decline in cardiorespiratory fitness after 30 years of aging was no worse than their decline after 3 weeks of strict bed rest.

"what they found was that their cardiorespiratory fitness after 30 years of aging was no worse than their cardiorespiratory fitness after 3 weeks of bed rest 30 years ago. So essentially, 3 weeks of bed rest is worse for your cardiovascular health, for your cardiorespiratory fitness, than 30 years of aging." (said at 0:07:44)

The 30-year follow-up of the Dallas Bed Rest and Training Study evaluated the five original male participants from 1966 to compare the impact of aging versus short-term strict bed rest on cardiorespiratory fitness (maximal oxygen uptake, VO2max). The study found that 3 weeks of bed rest at age 20 caused a greater reduction in work capacity and aerobic power than 30 years of natural aging. However, certainty is low due to the tiny sample size (n = 5 men).

0:13:21Rhonda Patrick (host)supportedmoderate

The 2018 JAMA study found that participants in the highest cardiorespiratory fitness group had a 20% lower all-cause mortality compared to those in the high-normal cardiorespiratory fitness group.

"even if you looked at the people in the very highest group and you compared them to people in the high normal—so they were still like on the high normal end, they're doing good—like those people in the highest group had a 20% lower all-cause mortality, so they were still doing better than the people that had a high normal cardiorespiratory fitness." (said at 0:13:21)

In a 2018 retrospective cohort study of 122,007 adults undergoing exercise treadmill testing published in JAMA Network Open (Mandsager et al.), cardiorespiratory fitness was inversely associated with all-cause mortality. Participants in the highest cardiorespiratory fitness category ('elite', ≥97.7th percentile) had an adjusted hazard ratio of 0.77 (95% CI, 0.63–0.95) for all-cause mortality compared with those in the 'high' category (75th–97.6th percentile), representing an approximate 23% (roughly 20%) reduction in mortality risk.

0:13:50Rhonda Patrick (host)supportedmoderate

The 2018 JAMA study found that people with low cardiorespiratory fitness had a mortality risk comparable to or worse than people with type 2 diabetes, heart disease, hypertension, or smoking history.

"the people in that low cardiorespiratory fitness group had a mortality risk that was comparable or even worse than people with diseases that we know are clearly bad for your health, like type 2 diabetes, um like heart disease, hypertension, even smokers." (said at 0:13:50)

A 2018 retrospective cohort study published in JAMA Network Open (Mandsager et al.) evaluated 122,007 patients undergoing exercise treadmill testing with a median follow-up of 8.4 years. The authors found that reduced cardiorespiratory fitness was strongly associated with increased risk-adjusted all-cause mortality, showing hazard ratios comparable to or exceeding those of traditional clinical risk factors including smoking (adjusted HR, 1.41), type 2 diabetes (adjusted HR, 1.40), and coronary artery disease (adjusted HR, 1.29).

0:21:12Brady Holmersupportedhigh

Studies demonstrate that exercise non-responders who do not improve their VO2 max with moderate-intensity training do show fitness improvements when exercise dose or intensity is increased with high-intensity interval training.

"when you give those people high-intensity interval training, everybody responds. There's some kind of recent studies that show that very well. You just increase their dose of exercise or their intensity or both, and they improve their fitness." (said at 0:21:12)

Published experimental trials show that cardiorespiratory fitness non-response is dose-dependent and can be abolished by increasing exercise volume or intensity. For example, a landmark randomized trial by Montero and Lundby (2017) demonstrated that while low doses of endurance training resulted in a high prevalence of VO2 max non-responders, increasing the exercise dose (adding training volume or higher frequency) completely eliminated non-response in 100% of participants, confirming that virtually all individuals respond when exercise stimulus is sufficiently increased.

0:28:54Brady Holmersupportedmoderate

Smartwatches and wrist-based heart rate sensors tend to become less accurate as exercise intensity increases.

"They've been, you know, validated against EKG and things like that. But as Levine mentioned and as others have kind of drawn caution, they tend to get less accurate as the intensity of exercise increases." (said at 0:28:54)

Published validation studies demonstrate that while wrist-worn optical heart rate sensors (photoplethysmography) correlate well with electrocardiogram (ECG) standards at rest and during low-intensity activity (such as walking), their measurement error increases and validity diminishes as exercise intensity and movement artifacts increase (such as during jogging, running, and vigorous exercise).

0:24:06Brady Holmersupportedhigh

The Borg Rating of Perceived Exertion (RPE) scale uses a range of 6 to 20 because multiplying the rating by 10 was designed to approximate the exerciser's heart rate in beats per minute.

"it's called the Borg RPE scale, and the 6 to 20 is essentially because the um initially the theory behind that scale was that you would just add a zero to whatever your RPE was, and that would correspond to your heart rate." (said at 0:24:06)

The original Borg Rating of Perceived Exertion (RPE) 6–20 scale was explicitly designed by Gunnar Borg to scale linearly with physiological strain, specifically constructed such that ratings from 6 (no exertion) to 20 (maximal exertion) multiplied by 10 roughly correspond to a healthy adult's heart rate range of 60 to 200 beats per minute. Exercise physiology literature consistently confirms this direct linear mapping and psychophysiological relationship between the 6–20 Borg scale and heart rate responses across various modalities.

0:32:20Brady Holmersupportedmoderate

Zone 2 exercise corresponds to the intensity where mitochondrial fat oxidation is maximized and blood lactate levels remain steady without continually rising.

"what zone two is maybe based on the exercise physiologist's definition of it, which would be it's kind of the intensity where you're maximizing your mitochondrial fat oxidation. It's a steady-state exercise less so than a threshold-like intensity. So your lactate levels—measuring lactate is kind of the accurate way to do it—so your lactate levels are steady, they're not increasing." (said at 0:32:20)

In exercise physiology, Zone 2 (within standard submaximal training models) is defined as the intensity corresponding to maximal fat oxidation (often termed FatMax) occurring below or near the first lactate threshold (LT1/aerobic threshold). At this intensity, blood lactate generation matches mitochondrial clearance, keeping blood lactate concentrations at a stable, steady-state baseline (typically around 1.5 to 2.0 mmol/L) without progressive accumulation.

0:33:21Brady Holmersupportedmoderate

Zone 2 exercise improves the mitochondria's ability to oxidize fat as its energy source because it is performed at the intensity of maximal mitochondrial fat oxidation.

"one of the main benefits reported for zone two is that you're improving your fat-burning capacity not only during exercise, but also your mitochondria's ability to oxidize fat as its energy source, because that's the intensity at which the fat oxidation in the mitochondria is maximal." (said at 0:33:21)

The speaker accurately describes the physiological rationale behind Zone 2 endurance training. Whole-body maximal fat oxidation (FatMax) typically occurs at low-to-moderate exercise intensities (approximately 45% to 65% of VO2max, corresponding to Zone 2). Training at these submaximal intensities stimulates mitochondrial adaptations—predominantly an increase in mitochondrial volume density and oxidative enzyme capacity—which enhances the capacity of skeletal muscle mitochondria to oxidize fatty acids during exercise and at baseline.

0:41:45Brady Holmersupportedhigh

The 80/20 training intensity model originated from training logs of elite athletes showing roughly 80% of sessions were at low intensity and 20% at high intensity.

"the origins of kind of the 80/20 are interesting and it was basically just looking at the training logs of elite athletes and seeing what they do. When you broke it down basically by intensity, 80% of their sessions tended to be in this lower, zone two-ish intensity, and then 20% of the sessions appeared to be in the higher-intensity training." (said at 0:41:45)

The 80/20 (or polarized) training intensity distribution concept originated from descriptive studies and training log analyses of elite endurance athletes (such as cross-country skiers, rowers, cyclists, and runners) pioneered by Stephen Seiler and colleagues. Observational quantification across multiple endurance disciplines consistently showed that athletes executed approximately 75% to 80% of their training sessions at low intensity (below the first ventilatory or lactate threshold) and roughly 15% to 20% at high intensity, with very little time spent in the moderate/threshold intensity zone.

0:44:39Brady Holmersupportedhigh

Studies show that previously unfit or sedentary individuals doing two to three Norwegian 4x4 sessions per week for 8 to 12 weeks can do so without injury and receive substantial fitness benefits.

"there are plenty of studies in exercise science where you take previously unfit people or people who aren't engaging in a lot of exercise, and for 8 to 12 weeks, you know, they're doing maybe two of the Norwegian 4x4 training sessions per week, sometimes even three sessions per week... it's clear that they can do it, that they can do a couple of these training sessions per week without getting injured, and they receive massive benefits from that." (said at 0:44:39)

Multiple randomized controlled trials investigating the Norwegian 4x4 aerobic high-intensity interval protocol (four 4-minute intervals at 85–95% of maximal heart rate with 3-minute active recovery periods) demonstrate that previously sedentary, unfit, or clinical populations can safely adhere to 2 to 3 sessions per week over 8 to 12 weeks without significant injury risk, resulting in substantial improvements in maximal oxygen uptake (VO2max) and cardiometabolic markers.

0:50:10Brady Holmersupportedmoderate

Interval durations in the 2 to 4-minute range appear particularly effective for improving VO2 max.

"you're doing the 4 minutes, which seem particularly good for improving like VO2 max, the like 2 to 4-minute range for intervals." (said at 0:50:10)

Exercise physiology literature and meta-analyses demonstrate that high-intensity interval training (HIIT) with long interval durations—typically in the 2- to 4- or 5-minute range (such as the classic 4 × 4-minute protocol at 90–95% maximal heart rate)—is particularly effective for increasing maximal oxygen uptake (VO2 max). These longer bouts allow individuals to spend sufficient cumulative time near or above 90% of VO2 max, leading to substantial gains in cardiorespiratory fitness compared to lower-intensity training.

0:52:30Rhonda Patrick (host)supportedhigh

The human heart begins to get stiffer around early middle age (ages 35 to 50), which impairs cardiac compliance and contributes to hypertension.

"how as we age, our heart becomes stiffer at around early middle age. This is like around, I guess it was it's more like 35 to 50 years of age. Crazy to think about that as being early middle age. Your heart starts to get stiffer, and that affects cardiac compliance, it affects hypertension." (said at 0:52:30)

The host's statement accurately summarizes published physiological findings on age-related changes in cardiac stiffness. Research measuring invasive left ventricular pressure-volume curves across age groups demonstrates that age-associated left ventricular stiffening begins during the transition from youth to early middle age (ages 35–49) and becomes manifest between ages 50 and 64, significantly reducing cardiac compliance. Furthermore, randomized clinical evidence shows that sedentary aging drives this increase in left ventricular stiffness during middle age, which impairs cardiac distensibility and increases risk for cardiovascular complications.

0:53:12Rhonda Patrick (host)supportedmoderate

Elevated blood glucose reacts with collagen in blood vessels and the myocardium via the Maillard reaction (glycation), leading to tissue cross-linking and vascular/cardiac stiffness.

"if we're sedentary, that glucose stays around in your vascular system, and it reacts with proteins, including collagen, which is lining our blood vessels, it's lining our myocardium, our pericardium, right? This is, you know, where our heart is. And that collagen, when it reacts with glucose in the Maillard reaction, it causes the protein, the collagen, to become stiffer, and so that affects the stiffness of our vascular system, of our heart, and also our blood vessels." (said at 0:53:12)

The host's statement accurately describes the pathophysiological process of non-enzymatic glycation (the Maillard reaction). Elevated circulating glucose non-enzymatically reacts with structural matrix proteins, primarily collagen, to form advanced glycation end-products (AGEs). These covalent cross-links increase collagen fiber rigidity and impair degradation, directly driving arterial and myocardial stiffness in conditions of hyper-glycemia, aging, and metabolic dysfunction.

0:53:45Rhonda Patrick (host)supportedmoderate

In late middle age (ages 50 to 65), the heart atrophies and shrinks in size in addition to becoming stiffer.

"As we start to get into late middle age, this would be like 50 to 65, in addition to our heart getting stiffer, our heart shrinks, so it atrophies. And so our heart is getting smaller and it's getting stiffer" (said at 0:53:45)

Published cardiovascular physiology research demonstrates that healthy, sedentary aging is characterized by progressive myocardial stiffening and left ventricular atrophy (reduction in mass and volume). Invasive hemodynamic studies from the Dallas Heart Study and related cohorts show that ventricular stiffening manifests during late middle age (ages 50 to 64), leading to decreased cardiac compliance and distensibility, alongside age-related cardiac volume contraction and atrophy that can be prevented or reversed by regular endurance exercise training.

0:54:15Rhonda Patrick (host)supportedmoderate

Senior Masters athletes who are physically active daily and compete nationally have cardiac structures that structurally resemble those of healthy 30-year-olds.

"One of the studies that he had done early on, which were done in Masters athletes—they are physically active every single day, and they're competing at a national level in many cases, so they're doing a lot of cardiovascular and aerobic exercise—their hearts structurally, so we're talking about seniors, so these are people that are older, their hearts looked like healthy 30-year-olds" (said at 0:54:15)

A landmark 2004 physiological study led by Benjamin Levine evaluated left ventricular compliance and structure in senior Masters endurance athletes (mean age ~68 years) compared with age-matched sedentary seniors and young sedentary controls (mean age ~29 years). Invasive catheterization and echocardiographic analysis revealed that while sedentary aging caused marked left ventricular stiffening, the left ventricular pressure-volume relationships and compliance curves of the senior Masters athletes were indistinguishable from those of healthy ~30-year-old controls.

0:56:10Brady Holmersupportedmoderate

Research by Dr. Ben Levine indicates that after age 70, it becomes nearly impossible to reverse age-related structural changes and stiffness of the heart through exercise.

"one of the, I think, craziest statistics that Levine cited was that after the age of 70, it became nearly impossible to reverse the structure of the heart, indicating that, you know, you basically need to do everything that you can before that age to improve the structure of your heart because after that, it takes an unsustainable maybe level of exercise to kind of reverse some of those structural changes" (said at 0:56:10)

Research led by Dr. Benjamin Levine directly supports the speaker's claim. In an interventional physiological study assessing previously sedentary older adults (mean age 70.6 ± 3 years), 1 year of progressive, vigorous endurance training improved aerobic fitness and arterial function but failed to reverse left ventricular stiffening or improve cardiac compliance. In contrast, a subsequent randomized controlled trial from Levine's laboratory demonstrated that 2 years of exercise training initiated in late middle age (ages 45–64) successfully reversed age-related cardiac stiffness and increased left ventricular compliance, indicating that the heart's dynamic stiffness becomes resistant to reversal if exercise intervention is delayed past age ~65–70.

0:57:12Brady Holmersupportedlow

An observational study by Dr. Ben Levine showed that exercising 1 to 2 days per week provided no protection against heart aging compared to sedentary adults, 4 to 5 days provided significant cardiovascular protection, and 5 to 6 days provided nearly complete protection comparable to Masters athletes.

"they found was that the people who exercised 1 to 2 days per week pretty much had hearts with the same structure as sedentary adults, so 1 to 2 days per week provided zero protection basically against heart aging. When you moved up to 2 to 3 and then 3 to 4 days per week, those groups had some protection compared to the sedentary adults for their heart structure, so the structure of their hearts were a little bit better than people who were sedentary. The 4 to 5 group, that's kind of when you experienced a significant level of cardiovascular protection with age, and then the 5 to 6-day per week exercisers had nearly complete protection; they were similar to the Masters athletes." (said at 0:57:12)

The claim accurately reflects cross-sectional research led by Dr. Benjamin Levine (Bhella et al., 2014, with subsequent arterial analyses in Shibata et al., 2018). In an observational cohort of 102 healthy older adults (>60 years old) stratified by lifelong exercise frequency, casual exercise (<2 to 3 sessions/week) failed to prevent age-related declines in left ventricular compliance and distensibility compared to sedentary aging. In contrast, 'committed' lifelong exercise (4 to 5 sessions/week) preserved youthful ventricular compliance and reduced central arterial stiffness, approaching the cardiovascular compliance observed in competitive Masters-level athletes (6 to 7 sessions/week). Certainty is low because the evidence comes from cross-sectional observational data with retrospective categorization of lifelong exercise habits.

1:02:26Rhonda Patrick (host)supportedhigh

A two-year exercise intervention trial in sedentary 50-year-olds reversed cardiac structural aging by approximately 20 years, restoring cardiac compliance and structure to levels comparable to 30-year-olds.

"It was a 2-year intervention trial where he and his colleagues took 50-year-olds that were otherwise healthy but sedentary... And they looked at the structure of their heart before starting this protocol, and then 2 years after this exercise protocol, they looked at their hearts again and found that in many aspects, like the cardiac compliance and a variety of different parameters that they looked at—the size of the heart and the stiffness, right, stretchiness of the heart—in many aspects had reversed in terms of their aging. In fact, their hearts were comparable to looking more like 30-year-olds. So they had essentially started this program and they had these 50-year-old-looking hearts with respect to the size and the compliance, and then after this 2-year exercise protocol had reversed 20 years of cardiac aging" (said at 1:02:26)

A prospective randomized controlled trial led by Dr. Benjamin Levine and colleagues (Howden et al., 2018, published in Circulation) evaluated 61 healthy, sedentary middle-aged adults (average age 53 ± 5 years) undergoing either 2 years of supervised progressive/high-intensity exercise training or an attention control regimen. The 2-year exercise program significantly reduced left ventricular myocardial stiffness (stiffness constant decreased from 0.072 to 0.051, p = 0.0018) and increased left ventricular end-diastolic volume and maximal oxygen uptake (+18%), effectively reversing the cardiac structural stiffening and compliance loss characteristic of sedentary aging to levels typically observed in much younger, active cohorts.

  • supports: Reversing the Cardiac Effects of Sedentary Aging in Middle Age-A Randomized Controlled Tri… (Circulation 2018) · cited 217x in the literature
    "In a prospective, parallel group, randomized controlled trial, we examined the effect of 2 years of supervised high-intensity exercise training on LV stiffness. Sixty-one (48% male) healthy, sedentary, middle-aged participants (53±5 years) were randomly assigned to either 2 years of exercise training (n=34) or attention control (control; n=27)... Vo 2 max increased by 18%... and LV stiffness was reduced (right/downward shift in the end-diastolic pressure-volume relationships; preexercise training stiffness constant 0.072±0.037 to postexercise training 0.051±0.0268, P =0.0018), whereas there was no change in controls... In previously sedentary healthy middle-aged adults, 2 years of exercise training improved maximal oxygen uptake and decreased cardiac stiffness." (abstract, methods, results, and conclusions, passage verified)
    pubmedfull study (doi)
1:08:24Brady Holmersupportedhigh

Intense exercise that elevates heart rate increases circulating markers of cardiac damage that require recovery time.

"Levine definitely stressed the importance of recovery not only just from a muscular perspective and your autonomic nervous system, but the cardiac and cardiovascular system also needs to recover. You know, when you stress it with a high heart rate, you do increase some markers of cardiac damage, and those also need time to recover." (said at 1:08:24)

Substantial systematic review and trial evidence demonstrates that strenuous or high-intensity exercise that elevates heart rate causes transient elevations in circulating biomarkers of cardiac damage, particularly high-sensitivity cardiac troponin T (hs-cTnT) and I (hs-cTnI). These markers typically peak within a few hours post-exercise and require a period of recovery (usually 24 to 48 hours or more) to return to baseline.

1:15:45Rhonda Patrick (host)supportedmoderate

When the volume of exercise is kept the same, high-intensity interval training results in greater mitochondrial biogenesis and density than low- to moderate-intensity continuous exercise.

"when the volume of exercise is kept the same, that mitochondrial density—so this is mitochondrial biogenesis, which is the creation of new mitochondria—was actually better after high-intensity interval training than more zone 2 low- to moderate-intensity type of training when the volume of exercise was the same." (said at 1:15:45)

When exercise volume or total work is strictly matched, high-intensity interval training (HIIT) generally stimulates greater signaling for mitochondrial biogenesis and larger increases in markers of mitochondrial content/density (such as citrate synthase activity and mass-specific respiration) than low- to moderate-intensity continuous training (MICT). Randomized physiological trials using within-subject work-matched models (such as bilateral single-leg cycling) demonstrated superior mitochondrial adaptations after HIIT compared to MICT. Furthermore, systematic reviews and meta-analyses show that interval training is substantially more time- and volume-efficient at increasing skeletal muscle mitochondrial content per hour of exercise performed compared to continuous endurance training.

1:17:07Rhonda Patrick (host)supportedmoderate

Higher-intensity, more vigorous exercise increases the prevalence of mitophagy relative to lower-intensity exercise.

"It seems as though the more vigorous the exercise, the more intense the exercise, the increased prevalence that you have of mitophagy happening." (said at 1:17:07)

Human skeletal muscle studies show that exercise-induced mitophagy (the autophagic removal and recycling of damaged mitochondria) is intensity-dependent, with high-intensity or vigorous exercise stimulating markers of mitophagy to a greater magnitude than lower-intensity or traditional continuous endurance exercise.

1:18:20Brady Holmersupportedhigh

Carnitine palmitoyltransferase (CPT) is the rate-limiting enzyme for transporting fatty acids into the mitochondria for beta-oxidation.

"fatty acid oxidation relies on, you know, mitochondrial content as well as your levels of this enzyme known as CPT or carnitine palmitoyltransferase, which is the rate-limiting enzyme for getting fatty acids into the mitochondria where they can be oxidized to produce energy." (said at 1:18:20)

Carnitine palmitoyltransferase (specifically CPT1, located on the outer mitochondrial membrane) is well established in biochemical literature as the primary rate-limiting enzyme responsible for converting long-chain acyl-CoA to acylcarnitine, enabling the transport of fatty acids across the mitochondrial membrane for subsequent beta-oxidation and energy production.

1:24:38Brady Holmersupportedmoderate

Studies of individuals habitually following a ketogenic diet show that their maximal fat oxidation occurs at approximately 85% of maximal exercise intensity.

"There's like the famous study where they looked at people habitually eating a ketogenic diet, and their max fat oxidation was at 85% of their exercise intensity, which is kind of high." (said at 1:24:38)

Studies evaluating endurance athletes habitually adapted to a ketogenic (low-carbohydrate, high-fat) diet demonstrate that peak fat oxidation shifts to substantially higher exercise intensities compared to athletes on high-carbohydrate diets. In the landmark FASTER trial of habitual keto-adapted ultra-endurance athletes, peak fat oxidation was 2.3-fold higher and occurred at 70.3 ± 6.3% VO2max (compared to 54.9% in high-carbohydrate athletes), with fat supplying 88% of energy during submaximal running. Subsequent investigations in keto-adapted endurance runners during interval protocols have documented peak fat oxidation rates occurring at approximately 86.4 ± 6.2% VO2max, with the metabolic crossover point shifting above 80% VO2max.

1:27:00Rhonda Patrick (host)supportedmoderate

Chronically elevated blood glucose levels react with collagen in cardiac tissue, causing stiffening of the myocardium and pericardium and lowering cardiac compliance.

"I mentioned that glucose dysregulation, if you're constantly having elevations in blood glucose levels, that can lead to the stiffening of your myocardium, of your pericardium, right? These have collagen in them and they react with glucose, and that leads to a lower cardiac compliance. Essentially, your heart is less stretchy." (said at 1:27:00)

Chronically elevated blood glucose promotes non-enzymatic glycation of extracellular matrix proteins (such as collagen), forming advanced glycation end-products (AGEs) and stable collagen cross-links. In cardiac tissue, this glycation and associated fibrotic remodeling increases myocardial and extracellular matrix stiffness, reducing left ventricular compliance and contributing to diastolic stiffness in diabetic heart disease.

1:28:13Rhonda Patrick (host)supportedlow

Lactate produced during intense exercise serves as a signaling molecule that promotes the translocation of GLUT4 glucose transporters to skeletal muscle cell membranes.

"And so that lactate actually is a signaling molecule to the muscle cells. The glucose transporters in the muscle then come up—it's called translocation—they come up to the cell surface of the muscle and they're open and primed and ready to take in a lot of glucose. And lactate is really key in that process. So if you're producing lactate by having a more intense workout, you're going to have more GLUT4 transporters that are translocating up to the muscle cell surface where they're ready to take in the glucose." (said at 1:28:13)

Preclinical and mechanistic evidence supports the claim that lactate functions as an active signaling molecule in skeletal muscle to stimulate GLUT4 translocation and glucose uptake independently of insulin signaling. Recent mechanistic work demonstrated that L-lactate binds its receptor (GPR81) in skeletal muscle, recruiting FARP1 and activating RAC1 to drive GLUT4 translocation to the cell surface, an axis that is upregulated following exercise. While the primary mechanistic demonstrations of lactate-induced GLUT4 translocation are derived from rodent and in vitro models, exercise-induced GLUT4 translocation to the plasma membrane is well-documented in humans.

1:15:14Rhonda Patrick (host)supportedhigh

Mature human red blood cells do not contain mitochondria.

"they're little tiny organelles that are inside of our cells—most of our cells, with the exception of red blood cells" (said at 1:15:14)

Mature mammalian erythrocytes (red blood cells) undergo programmed organelle clearance during terminal erythroid differentiation, including enucleation and selective mitophagy. Consequently, healthy mature red blood cells lack mitochondria as well as other organelles, relying exclusively on anaerobic glycolysis for energy production.

1:19:01Brady Holmersupportedhigh

Skeletal muscle contraction triggers the translocation of GLUT4 glucose transporters to the muscle cell membrane independently to facilitate glucose uptake.

"muscle contraction in itself is just so interesting in that it also causes the GLUT4 transporters to translocate to the cell membrane where they can suck up more glucose into the muscle." (said at 1:19:01)

Muscle contraction directly triggers the translocation of GLUT4 glucose transporters from intracellular storage compartments to the sarcolemma and transverse tubules via an insulin-independent signaling pathway (involving AMPK, Ca2+/CaMKII, and other mechanical and metabolic signals), facilitating accelerated glucose uptake into skeletal muscle cells.

1:23:15Brady Holmersupportedmoderate

During progressive exercise, energy substrate contribution reaches an equal 50% split between carbohydrates and fats at approximately 60% to 70% of maximum heart rate.

"And as you increase your exercise intensity, fat oxidation goes down, carbohydrate oxidation goes up, and then kind of in the middle somewhere, about 60-70% of your maximum heart rate, that's where you're getting 50% contribution from carbohydrate, 50% from fat." (said at 1:23:15)

The speaker accurately describes the physiological 'crossover concept' established in exercise metabolism literature. As exercise intensity increases, absolute and relative carbohydrate oxidation increases while lipid oxidation diminishes. The crossover point—defined as the power output where energy from carbohydrate-derived fuels surpasses energy from lipids (a 50/50 split)—typically occurs at moderate exercise intensities, generally between 45% and 75% of maximal aerobic capacity (roughly corresponding to 60% to 70% of maximum heart rate), shifting rightward with endurance training status.

1:31:05Brady Holmersupportedmoderate

Interval walking alternating between 75% and 60% intensity produces greater improvements in 24-hour glucose regulation, waist circumference, BMI, and HbA1c than continuous walking at 65% intensity.

"he mentioned the study where they basically just did two groups of walking, where one walked at a continuous intensity of 65% and the other group alternated intensities, 75% and 60%. So not even high-intensity interval training, they just did interval walking is what he called it, and they experienced much better improvements in, it was 24-hour glucose regulation and cardiometabolic risk factors, I think in things like waist circumference, their BMI, as well as like their HbA1c. All those things improved better with interval walking compared to just moderate-intensity walking" (said at 1:31:05)

Randomized controlled trials investigating interval-walking training (IWT; typically alternating repetitions of low/moderate and high intensity, such as alternating intervals vs. continuous moderate walking matched for energy expenditure) support the speaker's claim. In individuals with type 2 diabetes, 4 months of free-living interval-walking training produced significantly greater reductions in continuous glucose monitoring (CGM) mean and maximum glucose, body mass, and adiposity (including visceral fat), alongside improvements in insulin sensitivity, compared with energy expenditure-matched continuous walking training (which showed no significant improvements in glycemic control or body composition). Similar Japanese interval-walking protocols also demonstrate greater cardiometabolic and fitness improvements compared with continuous walking.

1:32:25Rhonda Patrick (host)supportedhigh

Brain-derived neurotrophic factor (BDNF) is produced in both skeletal muscle and the brain.

"So brain-derived neurotrophic factor is a growth factor, it's a neurotrophic factor. It's produced in the body, in the muscle, but also in the brain." (said at 1:32:25)

Brain-derived neurotrophic factor (BDNF) is a neurotrophin and growth factor that is abundantly synthesized in the central nervous system and is also expressed and produced peripherally in skeletal muscle cells (where its expression increases following contraction and exercise).

1:33:20Rhonda Patrick (host)supportedlow

Lactate produced during exercise crosses the blood-brain barrier and activates brain-derived neurotrophic factor in the brain.

"Lactate is one mechanism, because lactate has been shown to cross over through the blood-brain barrier and in the brain activate brain-derived neurotrophic factor." (said at 1:33:20)

Preclinical evidence demonstrates that lactate released by skeletal muscle during exercise crosses the blood-brain barrier and induces brain-derived neurotrophic factor (BDNF) expression and TRKB signaling in the hippocampus (via a SIRT1/PGC1a/FNDC5 pathway). Because direct mechanistic demonstration of this muscle-to-brain signaling cascade relies predominantly on animal models, the overall body of evidence is rated as low certainty.

1:33:55Rhonda Patrick (host)supportedmoderate

A 10-minute high-intensity interval training (HIIT) workout has been shown to improve cognition.

"Even the 10-minute high-intensity interval training workout has been shown to improve cognition." (said at 1:33:55)

Randomized crossover trials and systematic reviews confirm that brief, acute bouts of high-intensity interval exercise (including 10-minute protocols consisting of short sprint intervals and rest periods) lead to acute improvements in cognitive performance, particularly executive function and inhibitory control (e.g., Stroop task reaction time).

1:34:35Rhonda Patrick (host)supportedmoderate

A 20-minute workout at 80% maximum heart rate increases BDNF, and doubling the duration to 40 minutes produces an even more robust increase.

"even if you're doing a 20-minute workout and you want to be at least like 80% your max heart rate for those 20 minutes, more like a zone 3-ish kind of workout, right, that's been shown to robustly increase brain-derived neurotrophic factor. If you double that to 40 minutes, then you get an even more robust increase." (said at 1:34:35)

Acute cardiovascular exercise at moderate-to-vigorous intensity (such as 80% maximum heart rate) consistently leads to transient, statistically significant increases in circulating brain-derived neurotrophic factor (BDNF). Systematic reviews and meta-analyses show that acute exercise elicits a robust elevation in peripheral BDNF levels (pooled effect size Hedges' g = 0.48, p < 0.001), with larger increases observed following higher exercise intensities and extended aerobic bouts.

1:43:18Rhonda Patrick (host)supportedmoderate

Short exercise snacks timed around meals improve glucose regulation in individuals with type 2 diabetes or metabolic syndrome.

"And there's also been some evidence on this published looking at mostly people with metabolic dysfunction, like type 2 diabetes, metabolic syndrome, and how even doing something timed around a meal—and it doesn't have to be long, it can be a short, again, you're doing some bodyweight squats or burpees or jumping jacks, whatever—it improves glucose regulation, right?" (said at 1:43:18)

Randomized crossover trials and systematic reviews confirm that brief, intermittent bouts of physical activity ("exercise snacks"), including bodyweight movements or short intense intervals timed around meals, significantly improve postprandial glucose excursions, glycemic variability, and overall glucose regulation in individuals with insulin resistance and type 2 diabetes.

1:46:38Rhonda Patrick (host)supportedmoderate

After peak muscle mass in early adulthood, muscle mass declines on average by approximately 8% per decade.

"and then after that peak, you start to decline on average about 8% per decade. So this age-related decline in muscle mass is often referred to as sarcopenia" (said at 1:46:38)

Scientific literature on age-related muscle loss (sarcopenia) commonly reports that following peak muscle mass in early adulthood, skeletal muscle declines at an estimated rate of approximately 3% to 8% per decade (averaging near 8% per decade up to age 70), after which the rate of loss accelerates further (to roughly 13% to 24% per decade).

1:47:20Rhonda Patrick (host)supportedmoderate

At age 70, the rate of age-related muscle mass loss increases to approximately 15% per decade.

"and then as you reach the age of 70, that goes up to 15% per decade." (said at 1:47:20)

The claim is supported by the literature on primary (age-related) sarcopenia. Studies evaluating age-related body composition trajectories establish that skeletal muscle mass loss typically begins after the fourth decade at an estimated rate of approximately 8% per decade, which accelerates to around 15% per decade after the age of 70.

1:47:30Rhonda Patrick (host)supportedmoderate

Muscle strength declines annually by 3% to 4% per year in men and 2.5% to 3% per year in women.

"strength declines annually for men about 3 to 4% per year, and then for women it's about 2.5 to 3% your strength decreases per year on average." (said at 1:47:30)

The statement directly reflects landmark prospective data from the Health, Aging and Body Composition (Health ABC) study examining longitudinal changes in muscle strength in older adults (aged 70–79 years). In this cohort (n = 1,880), annualized rates of knee extensor strength decline were 3.4% to 4.1% per year in men (3.4% in white men, 4.1% in Black men) and 2.6% to 3.0% per year in women (2.6% in white women, 3.0% in Black women).

1:49:10Brady Holmersupportedmoderate

Muscle power starts declining earlier and declines more rapidly with age than muscle mass or muscle strength.

"what's unique about muscle power is that it seems to start declining earlier and then it declines more rapidly than muscle mass or muscle strength." (said at 1:49:10)

Cross-sectional and longitudinal physiological studies consistently demonstrate that muscle power declines earlier in the lifespan (starting as early as the third to fourth decade) and at a faster rate (approximately 8-10% per decade or more) than muscle strength (approximately 1-3% per year in older age, or ~5-8% per decade) and muscle mass (~3-4% per decade). This accelerated loss is attributed to a combination of muscle mass loss, selective atrophy and denervation of type II (fast-twitch) motor units, and reductions in maximal contractile shortening velocity.

1:56:08Brady Holmersupportedmoderate

Psychological stress increases injury risk and compromises athletic training performance.

"there are several studies showing like psychological stress, it increases your injury risk, your training session is going to be compromised." (said at 1:56:08)

Extensive research in sports psychology and sports medicine supports the claim that psychological stress elevates injury risk and impairs recovery and athletic performance. Systematic reviews and meta-analyses demonstrate that life event stress, daily hassles, and psychological distress predict higher sports injury incidence across various athletic populations. Theoretical frameworks, such as Williams and Andersen's stress-and-injury model, describe mechanisms including peripheral vision narrowing, distractibility, and elevated muscle tension during high stress, which compromise movement execution and increase vulnerability to acute and overuse injuries.

1:57:40Rhonda Patrick (host)supportedmoderate

Multi-joint compound resistance exercises stimulate bone remodeling and improve bone mineral density and bone mass more than single-joint exercises.

"It's also, again, going to improve bone density more because you're putting more force and stressing your bones more with those types of exercises, and that causes the adaptation of bone remodeling. So you're going to have improvements in bone mineral density and bone mass as well." (said at 1:57:40)

Mechanical loading is a primary stimulus for bone remodeling and osteogenesis. Multi-joint compound resistance exercises (such as squats, deadlifts, and overhead presses) allow for the application of high mechanical forces and axial loading across major skeletal sites, notably the lumbar spine and proximal femur. Randomized and clinical trials demonstrating bone mineral density (BMD) accrual consistently utilize high-intensity, multi-joint resistance training protocols to induce bone remodeling and improve BMD and bone structural strength.

1:59:00Rhonda Patrick (host)supportedhigh

When lifting at or above 85% of 1-rep max for strength training, resting 2 to 5 minutes between sets is required to replenish phosphocreatine stores to produce ATP for subsequent sets.

"when you're doing strength training, you're going to get up to about an 85% or more of your 1-rep max... you're going to require a longer recovery. So Dr. Schoenfeld mentioned between 2 to 5 minutes... your body literally needs time to replenish the phosphocreatine stores in order to produce, you know, the ATP to do that next set." (said at 1:59:00)

The speaker's statement is supported by exercise physiology and resistance training literature. Heavy strength training (at or above ~85% of 1-rep maximum) relies primarily on the phosphagen (ATP-phosphocreatine) energy system. Phosphocreatine stores are rapidly depleted during high-intensity contractions and require approximately 2 to 5 minutes (with near-complete resynthesis occurring within 3 to 5 minutes) to replenish between sets. Systematic reviews and randomized trials examining rest interval lengths confirm that resting 2 to 5 minutes allows lifters to maintain volume and intensity, resulting in significantly greater absolute strength adaptations compared to shorter rest intervals.

1:49:00Brady Holmersupportedmoderate

Muscle power assessed via a sit-to-stand chair test is correlated with longevity.

"one of the ways to measure it is using just like a simple sit-to-stand test on a chair, but like how quickly can you do that? So how quickly can you sit down and rise from a chair? Even in the study that we covered, that's how they assessed muscle power and showed that it was correlated with actually longevity" (said at 1:49:00)

Prospective cohort studies have repeatedly demonstrated that muscle power assessed via sit-to-stand chair tests (such as the 5-repetition or 30-second chair rise test, which measures how quickly a person can stand up repeatedly) is significantly correlated with reduced all-cause mortality and increased longevity in older adults.

2:01:13Brady Holmersupportedhigh

Dr. Brad Schoenfeld recommends resting 2 to 5 minutes between sets when training for strength.

"And so that's why Dr. Schoenfeld recommended rest anywhere from 2 to 5 minutes, again based on how much weight you're lifting... But 2 to 3 minutes is probably the minimum, anywhere up to 5, and he really emphasized just don't rush the rest period, especially when training for strength" (said at 2:01:13)

Dr. Brad Schoenfeld's research and published work support resting at least 2 to 3 minutes (and up to 5 minutes) between sets to maximize strength gains. In a randomized controlled trial led by Schoenfeld (PMID: 26605807), resistance-trained men using 3-minute inter-set rest intervals achieved significantly greater 1RM strength increases in the squat and bench press compared to those using 1-minute rest intervals. Furthermore, systematic reviews co-authored by Schoenfeld (e.g., PMID: 28933024) conclude that longer rest intervals (> 2 minutes) are necessary to maximize strength gains in resistance-trained individuals.

2:06:24Brady Holmersupportedhigh

Research indicates that training to muscle failure is not necessary to optimize strength or hypertrophy compared to leaving repetitions in reserve.

"It appears, yeah, training to failure doesn't appear to be necessary to optimize strength or hypertrophy. It appears at least, you know, pretty equal to training with, you know, a couple reps in reserve" (said at 2:06:24)

Multiple systematic reviews and meta-analyses of randomized resistance training trials indicate that training to momentary muscular failure is not required to maximize strength gains or muscle hypertrophy. When training volume is equated, training with repetitions in reserve (non-failure) produces strength and hypertrophy adaptations comparable to training to failure.

2:07:45Brady Holmersupportedmoderate

Training with 1 to 3 repetitions in reserve produces equivalent gains in strength and hypertrophy compared to training to complete failure.

"And training with one to three reps in reserve appears to be just as good as training to failure if your goal is to maximize strength or muscle hypertrophy." (said at 2:07:45)

Systematic reviews and meta-analyses comparing resistance training to failure versus non-failure (leaving repetitions in reserve, or RIR) indicate that training to complete failure is not necessary to maximize strength or muscle hypertrophy. For strength, multiple meta-analyses demonstrate comparable gains regardless of whether sets are taken to failure or stopped several repetitions short. For hypertrophy, meta-analyses comparing momentary muscular failure to non-failure show no significant difference in muscle growth, especially when training volume is equated, although exploratory meta-regressions suggest training close to failure (within ~0–3 RIR) optimizes hypertrophic adaptations compared to terminating sets far from failure.

2:10:38Brady Holmersupportedmoderate

The heart rate elevation during strength training is primarily driven by the autonomic nervous system via central command rather than metabolic demand and muscle blood flow requirements.

"During strength training, though, the drive for the increase in heart rate is mainly from the autonomic nervous system. So it's driven by central command... versus a metabolic demand increasing in the muscle or like the drive for increased blood flow during aerobic exercise." (said at 2:10:38)

During resistance and isometric exercise, the elevation in heart rate is primarily governed by central command—a feedforward neural signal originating in higher brain centers that rapidly alters autonomic outflow (initial parasympathetic/vagal withdrawal followed by sympathetic activation) and resets the cardiac baroreflex. In contrast to dynamic aerobic exercise, where sustained heart rate increases closely match systemic metabolic demand and large-scale muscle blood flow needs, the cardiovascular adjustments to strength contractions are predominantly mediated by this central autonomic drive and the exercise pressor reflex.

2:13:10Brady Holmersupportedhigh

Meta-analyses demonstrate that muscle hypertrophy outcomes are equal when comparing machine-based exercises to free weights.

"Using machines versus free weights, he didn't seem to be concerned with that either and even cited some meta-analyses showing, you know, is hypertrophy better with machines or free weights? Seemed to be equal." (said at 2:13:10)

Systematic reviews and meta-analyses directly comparing machine-based exercises to free weights have found no significant differences in muscle hypertrophy outcomes between the two modalities. While strength gains exhibit modality-specific testing effects (training with free weights leads to larger strength gains on free-weight tests, and vice versa), changes in muscle size are equivalent.

2:18:25Rhonda Patrick (host)supportedhigh

During caloric restriction for weight loss, up to 30% of the total weight lost can come from lean body mass or muscle.

"And he cited a study that even up to 30% of the weight that's lost can come from muscle or lean body mass." (said at 2:18:25)

During diet-induced weight loss (caloric restriction without concomitant resistance exercise), fat-free mass (which includes skeletal muscle, water, and organ tissue) typically accounts for approximately 20% to 30% of total weight lost. A 2026 systematic review and meta-analysis of randomized clinical trials found that in diet-only interventions achieving at least 10% weight loss, fat-free mass accounted for an average of 22.3% of total weight lost, with higher proportions (around 30% or more) frequently observed depending on the severity of the deficit, baseline body composition, and lack of exercise.

2:22:11Brady Holmersupportedmoderate

Sleep deprivation impairs lean mass gains and makes body fat loss more difficult during training.

"He cited a study showing that if you don't get enough sleep, it actually will hamper your gains in lean mass and it can make kind of body fat loss a little bit more stubborn, so harder." (said at 2:22:11)

A randomized crossover study evaluated the effect of sleep curtailment (5.5 hours vs. 8.5 hours of sleep opportunity per night) during 14 days of moderate caloric restriction in overweight adults. Sleep restriction reduced the proportion of weight lost as fat by 55% (0.6 kg vs. 1.4 kg) and increased the loss of fat-free/lean mass by 60% (2.4 kg vs. 1.5 kg), shifting substrate utilization away from fat oxidation. While direct trials on hypertrophy during training show mixed results depending on the severity of sleep debt, controlled trial evidence confirms that insufficient sleep compromises fat loss and worsens lean mass loss during an energy deficit.

2:26:19Brady Holmersupportedhigh

Static stretching prior to resistance training provides no performance benefit and can impair performance compared to dynamic warmups.

"And yeah, in fact, static stretching as compared to dynamic stretching actually appears to have no performance benefit, if anything is detrimental. So standing there and doing, you know, your little arm exercises, that's actually hurting your performance." (said at 2:26:19)

The speaker claims that static stretching prior to resistance training provides no performance benefit and can impair performance compared to dynamic stretching. Systematic reviews and meta-analyses support this assertion: pre-exercise static stretching has been consistently shown to offer no performance benefit and induces acute maximal strength and explosive performance deficits (particularly with longer stretch durations), whereas dynamic stretching or dynamic warm-ups preserve or enhance subsequent strength, power, and dynamic performance.

2:27:22Brady Holmersupportedhigh

Performing 15-minute resistance training micro-workouts 6 to 8 times per week yields similar strength and hypertrophy gains to 3 to 4 longer sessions of equivalent total volume.

"Dr. Schoenfeld did cite a study on these sort of micro resistance training workouts where people performed 15 minutes of resistance training six to eight times per week versus say doing the same resistance training, same volume, same exercises three to four times a week for say, you know, 30 to 40 minutes. They achieved the same level of strength and hypertrophy." (said at 2:27:22)

Systematic reviews and meta-analyses examining resistance training frequency (including research co-authored by Dr. Brad Schoenfeld) demonstrate that when weekly training volume is equated, training frequency does not significantly affect gains in muscular strength or hypertrophy. Splitting a given weekly volume into more frequent, shorter sessions (e.g., higher frequency micro-sessions) produces comparable hypertrophic and strength adaptations to performing fewer, longer sessions.

2:29:54Brady Holmersupportedmoderate

Resistance training performed twice per week for 30 minutes per session is sufficient to maintain or increase muscle strength.

"Two times per week, 30 minutes at a time seems to be compatible with maintaining or even building strength. He cited multiple studies, and even recently they have published a couple showing that just engaging in resistance training two times per week, 30 minutes, that seems to be probably the bare minimum if you want to maintain or increase your muscle strength." (said at 2:29:54)

The published literature on time-efficient resistance training supports the claim that low-frequency, low-duration resistance exercise (such as two ~30-minute sessions weekly focusing on compound movements or utilizing time-saving techniques like supersets) provides sufficient volume to maintain or increase muscular strength, especially when performing at least 4 sets per muscle group per week.

2:31:40Rhonda Patrick (host)supportedlow

Observational research shows that individuals who combine regular exercise with sauna bathing have lower all-cause mortality than those who exercise without sauna use.

"So there's been observational data showing people that exercise and use the sauna have a lower all-cause mortality than people that exercise and don't use the sauna." (said at 2:31:40)

Observational evidence from the Kuopio Ischaemic Heart Disease (KIHD) prospective cohort study supports this claim. In a study of 2,277 middle-aged Finnish men followed for a median of 26.1 years, researchers evaluated the combined effects of cardiorespiratory fitness (CRF, reflecting regular aerobic exercise) and frequency of sauna bathing (FSB). Compared to the baseline reference group (low CRF and low FSB), men with high CRF and frequent sauna bathing (3–7 sessions/week) had a lower risk of all-cause mortality (hazard ratio 0.60; 95% CI, 0.48–0.76) and cardiovascular mortality (hazard ratio 0.42; 95% CI, 0.28–0.62) than those with high CRF and low sauna frequency (hazard ratio 0.63 for all-cause mortality and 0.50 for cardiovascular mortality). Because this finding is based on observational prospective cohort data in men, the certainty of evidence is low.

2:31:52Rhonda Patrick (host)supportedmoderate

An interventional study by Dr. Jari Laukkanen found that adding post-exercise sauna bathing to stationary cycling improved cardiorespiratory fitness, blood pressure, and cholesterol more than cycling alone.

"he's also done some interventional studies where he's taken two groups of people and put them on an exercise protocol, aerobic exercise on a stationary bike, and then only half of that group then went into a sauna after the exercise, and he measured cardiorespiratory fitness and found that people that use the sauna in addition to aerobic exercise improved their cardiorespiratory fitness even more than people that uh only did the exercise. And there were other cardiometabolic parameters that were also improved: cholesterol was improved, blood pressure was improved more as well." (said at 2:31:52)

An 8-week randomized controlled trial co-authored by Dr. Jari Laukkanen evaluated 47 sedentary adults with cardiovascular risk factors assigned to regular exercise plus post-exercise sauna bathing (EXS), regular exercise alone (EXE), or a control group. Compared with exercise alone, the exercise plus sauna group experienced a significantly greater improvement in cardiorespiratory fitness (an additional +2.7 mL/kg/min in VO2max), a greater reduction in systolic blood pressure (-8.0 mmHg), and a greater reduction in total cholesterol levels.

2:20:38Brady Holmersupportedhigh

Consuming a higher protein diet increases the thermic effect of food, causing an increase in caloric expenditure required for digestion.

"eating protein—a higher protein diet tends to have a few benefits: so not only the lean mass maintenance benefits that come with protein, but it also has a thermogenic effect. So protein, you know, when you eat a higher protein diet, it kind of causes your body to increase its caloric burn for digestive purposes, which may lead to a slightly greater caloric deficit." (said at 2:20:38)

Dietary protein has a well-established higher thermic effect of food (also termed diet-induced thermogenesis) compared to carbohydrates and fats. Meta-analyses of randomized controlled crossover trials confirm that higher-protein meals and diets significantly increase postprandial diet-induced thermogenesis and total daily energy expenditure compared to isocaloric lower-protein diets, which contributes to a modest increase in net caloric expenditure.

2:28:15Brady Holmersupportedmoderate

Concurrent aerobic and resistance training does not cause an inherent molecular interference effect that blunts muscle adaptations when session quality is maintained.

"As for the whole like interference effect, people sometimes get worried about like, oh, is doing aerobic exercise and strength training going to compromise my gains due to the molecular interference of the different signals that govern like endurance adaptations and strength? That whole thing has been kind of dismissed. There's not really any such thing. It only occurs if you're obviously compromising the quality of your sessions by doing them both on the same day." (said at 2:28:15)

Human exercise physiology research does not support the classical molecular interference hypothesis, which proposed that endurance-activated signaling pathways (such as AMPK) directly inhibit resistance-induced anabolic signaling pathways (such as mTORC1) to blunt muscle adaptations under controlled conditions. Acute human crossover studies evaluating concurrent training protocols demonstrate that performing aerobic exercise alongside resistance exercise does not blunt post-exercise mTOR phosphorylation or anabolic signaling pathways. Systematic reviews and meta-analyses show that whole-muscle hypertrophy is generally preserved during concurrent training compared with resistance training alone, and that decrements in strength or power adaptations are primarily driven by residual neuromuscular fatigue, exercise volume, frequency, and session scheduling rather than direct molecular antagonism.

2:33:34Brady Holmersupportedmoderate

Sauna use improves exercise performance in both hot and temperate (normal) weather conditions.

"it also improves your exercise performance not only in the heat, you know, which kind of makes sense, you're using the sauna, you're becoming more heat acclimated, but it also improves your performance just in normal weather or like not hot weather" (said at 2:33:34)

The claim is supported by scientific evidence. Studies evaluating post-exercise sauna exposure demonstrate improvements in exercise performance markers and tolerance under both hot and temperate (cool/normal) conditions. For example, Kirby et al. (2021) demonstrated that 3 weeks of post-exercise sauna bathing in trained middle-distance runners improved running heat tolerance in hot conditions (40 °C) while also significantly increasing VO2max and running speed at lactate threshold during exercise testing in temperate conditions (18 °C). Similarly, Scoon et al. (2007) reported that 3 weeks of post-exercise sauna bathing in competitive runners increased treadmill running time to exhaustion by 32% (equivalent to a ~1.9% endurance time trial performance enhancement) when tested under temperate laboratory conditions, largely mediated by plasma volume expansion.

2:35:17Rhonda Patrick (host)supportedlow

Observational data from Dr. Laukkanen shows that using the sauna 4 to 7 times per week is associated with up to a 50% reduction in cardiovascular-related mortality and a 40% reduction in all-cause mortality.

"If you get up to four times a week, then you're really getting maximal benefits of four to seven times a week. People are getting reductions up to 50% in their cardiovascular-related mortality, 40% related to reductions in their all-cause mortality." (said at 2:35:17)

A prospective cohort study led by Dr. Tanjaniina Laukkanen and Dr. Jari Laukkanen (the Kuopio Ischemic Heart Disease Risk Factor Study, PMID 25705824, tracking 2,315 middle-aged Finnish men over a median of 20.7 years) reported findings that match these exact percentages. Compared to men having one sauna bathing session per week, men having 4 to 7 sessions per week experienced significant reductions in fatal cardiovascular events and all-cause mortality (specifically, an adjusted HR of 0.50 for fatal CVD, representing a 50% risk reduction, and an adjusted HR of 0.60 for all-cause mortality, representing a 40% risk reduction). As this is observational data in a cohort of Finnish men, certainty regarding causality is rated low due to potential residual confounding and indirectness.

2:36:17Rhonda Patrick (host)supportedlow

In a preliminary small study, sauna use following resistance training increased mTOR signaling molecules involved in muscle hypertrophy.

"there has been at least some preliminary evidence in one small study that people that got in the sauna after the resistance training protocol increased signaling molecules that are involved, mTOR signaling molecules that involved in muscle hypertrophy." (said at 2:36:17)

The speaker accurately characterizes the literature as preliminary evidence from small experimental studies. Clinical trials investigating heat application combined with resistance exercise have demonstrated enhanced activation of the Akt-mTOR signaling cascade (a pathway governing muscle protein synthesis and hypertrophy) in human skeletal muscle. For example, a randomized crossover trial in 8 young men found that heat stress applied around resistance exercise significantly elevated the phosphorylation of Akt, mTOR, and downstream ribosomal protein S6 compared to exercise alone. Similarly, a 2023 study found that a single session of whole-body heat stress following resistance exercise increased activation of the Akt-mTOR pathway in resistance-trained individuals.

2:36:30Rhonda Patrick (host)supportedmoderate

In a human trial involving muscle immobilization, local heat exposure resulted in participants losing almost 40% less muscle mass compared to controls.

"There's also been another trial in humans that underwent—I mean, it was experiments that are done where they're they immobilize a muscle for a period of time and they look at atrophy after that, right? Disuse atrophy is is what it's it's called. And it seems as the um heat exposure, at least at the local level in this in this regard for this study, people that had the heat exposure were about almost 40% less likely to to lose their they lost 40% less of of their muscle mass" (said at 2:36:30)

A controlled human trial (n=23) by Hafen et al. (2019) evaluated the effect of daily 2-hour local heat therapy (pulsed shortwave diathermy) during 10 days of lower-limb immobilization. Participants receiving sham treatment lost 7.6% of vastus lateralis whole-muscle cross-sectional area, whereas those receiving daily heat treatment lost 4.5%, representing an approximate 41% attenuation in muscle cross-sectional area loss (along with a 46% attenuation in myofiber cross-sectional area reduction, -10.8% vs. -5.8%).

2:37:05Rhonda Patrick (host)supportedmoderate

Sauna exposure elevates growth hormone levels.

"Growth hormone is elevated when you're getting the sauna, and that can have aspects for recovery as well." (said at 2:37:05)

Sauna exposure stimulates an acute and transient rise in circulating growth hormone (GH) and growth hormone-releasing hormone (GHRH) levels. Multiple physiological studies have documented that acute hyperthermic stress in a Finnish sauna significantly increases plasma GH concentrations in healthy young adults, with hormone levels typically returning to baseline within a few hours post-exposure.

2:37:34Brady Holmersupportedhigh

Deliberate cold exposure immediately following resistance exercise blunts hypertrophic benefits and muscle protein synthesis.

"getting in cold immediately after resistance exercise in particular seems to blunt some of the hypertrophic benefits... Muscle muscle protein synthesis all goes down if you get in the cold right afterwards." (said at 2:37:34)

Deliberate cold water immersion performed immediately or shortly after resistance exercise has been shown across multiple randomized human trials to attenuate acute and daily myofibrillar protein synthesis (MPS) rates, blunt anabolic signaling pathways (such as mTORC1 and p70S6K phosphorylation), and reduce long-term muscle fiber hypertrophy compared to active or passive recovery controls.

2:39:28Rhonda Patrick (host)supportedmoderate

Research by Dr. Chris McGlory showed that 5 grams per day of omega-3 fatty acids reduced disuse muscle atrophy by almost 50% in women.

"Dr. Chris McGlory came on the podcast and talked about some of his research using high-dose omega-3, so was about 5 grams a day, which is um a little bit higher than what is prescribed for some people for different cardiometabolic reasons, was able to prevent or cut disuse atrophy almost by 50% in in this case it was in in women." (said at 2:39:28)

A randomized controlled trial led by Dr. Chris McGlory (PMID 30629458) evaluated 20 healthy young women undergoing 2 weeks of unilateral limb immobilization preceded by 4 weeks of supplementation with either 5 g/day of omega-3 fatty acids or a sunflower oil control. Following immobilization, skeletal muscle volume loss was significantly lower in the omega-3 group compared to the control group (8% vs. 14% reduction, P < 0.05), representing a relative reduction in disuse atrophy of approximately 43% (close to 50%).

2:40:42Brady Holmersupportedlow

Omega-3 fatty acids can prevent cardiac injury biomarkers after endurance running or downhill running.

"I think there was a study showing omega-3 fatty acids could prevent some of the um cardiac injury biomarkers after endurance running or after downhill running." (said at 2:40:42)

A randomized trial in 24 male long-distance runners examined the effect of 3 weeks of omega-3 polyunsaturated fatty acid supplementation (3,000 mg/day) versus placebo before a downhill running exercise protocol. The study found that omega-3 supplementation significantly increased erythrocyte membrane omega-3 content and was associated with lower post-exercise concentrations of cardiac damage biomarkers (including CK-MB, high-sensitivity troponin T, and heart-type fatty acid binding protein) and inflammatory mediators compared to placebo. However, the evidence base is limited by a small sample size from a single trial.

2:45:00Brady Holmersupportedmoderate

A recent study showed that delaying protein intake versus consuming it immediately post-exercise leads to similar gains in muscle hypertrophy and strength.

"In fact, there was just a recent study that came out that showed delaying protein intake versus immediately after, they both lead to similar gains in hypertrophy and strength." (said at 2:45:00)

Meta-analytic and experimental evidence evaluates whether timing protein intake immediately post-workout versus delaying intake (or providing equal daily protein at different intervals) alters muscle adaptations. A comprehensive meta-analysis of randomized trials (Schoenfeld et al., 2013) demonstrated that when controlling for total daily protein intake, protein timing (immediate vs. delayed/distant from exercise) has no significant effect on muscle hypertrophy or strength. Rather, meeting total daily protein requirements is the primary driver of resistance training adaptations.

2:45:34Brady Holmersupportedhigh

A study by Luc van Loon showed that 100 grams of protein consumed in a single meal can be digested, absorbed, and utilized for muscle protein synthesis.

"he also said that, you know, if you're just a two-meal-per-day person or even a one-meal-per-day person, you know, if you want to eat 100 grams of protein at once, that could be digested, absorbed, used for muscle protein synthesis. They published a kind of popular study recently showing that" (said at 2:45:34)

A 2023 randomized metabolic study led by Luc van Loon's research group (Trommelen et al.) evaluated the ingestion of 100 g versus 25 g of milk protein following resistance exercise using quadruple stable isotope tracers over a 12-hour recovery period. The study demonstrated that consuming 100 g of protein resulted in sustained plasma amino acid availability and significantly higher, more prolonged myofibrillar and muscle connective protein synthesis rates compared to 25 g, showing that large protein doses can be digested, absorbed, and utilized for muscle protein synthesis without an apparent short-term ceiling.

  • supports: The anabolic response to protein ingestion during recovery from exercise has no upper limi… (Cell reports. Medicine 2023) · cited 78x in the literature
    "Using a comprehensive quadruple isotope tracer feeding-infusion approach, we show that the ingestion of 100 g protein results in a greater and more prolonged (>12 h) anabolic response when compared to the ingestion of 25 g protein. We demonstrate a dose-response increase in dietary-protein-derived plasma amino acid availability and subsequent incorporation into muscle protein. Ingestion of a large bolus of protein further increases whole-body protein net balance, mixed-muscle, myofibrillar, muscle connective, and plasma protein synthesis rates." (abstract, results, passage verified)
    pubmedfull study (doi)
2:47:40Brady Holmersupportedhigh

A daily intake of 5 grams of creatine monohydrate will saturate muscle creatine stores after about a month without requiring an initial loading phase.

"even 5 grams per day after a while will probably saturate your muscle creatine stores... After about a month or so, that's kind of when the benefits might start to appear, because that's when your muscle stores are are saturated." (said at 2:47:40)

Clinical evidence demonstrates that consuming a low daily maintenance dose of creatine (3 to 5 grams per day) without an initial high-dose loading phase fully saturates skeletal muscle creatine stores over approximately 28 days (about one month), achieving muscle total creatine concentrations comparable to traditional loading protocols (such as 20 g/day for 5-6 days).

  • supports: Muscle creatine loading in men. (Journal of applied physiology (Bethesda, Md. : 1985) 1996) · cited 815x in the literature
    "A similar, but more gradual, 20% increase in muscle total creatine concentration was observed over a period of 28 days when supplementation was undertaken at a rate of 3 g/day. In conclusion, a rapid way to "creatine load" human skeletal muscle is to ingest 20 g of creatine for 6 days. This elevated tissue concentration can then be maintained by ingestion of 2 g/day thereafter. The ingestion of 3 g creatine/day is in the long term likely to be as effective at raising tissue levels as this higher dose." (abstract, results and conclusion, passage verified)
    pubmedfull study (doi)
2:21:47Rhonda Patrick (host)supportedhigh

The Recommended Dietary Allowance (RDA) for dietary protein is 0.8 grams per kilogram of body weight per day.

"how the RDA for protein, which is 0.8 grams per kilogram body weight, um does not appear to be enough for maintaining muscle mass, particularly if you are engaging in resistance training." (said at 2:21:47)

The Recommended Dietary Allowance (RDA) for dietary protein in healthy adults is established at 0.8 g/kg body weight/day. Systematic reviews and meta-analyses of randomized controlled trials demonstrate that while 0.8 g/kg/day is generally sufficient to maintain lean mass in sedentary, unstressed adults, it is suboptimal under conditions of anabolic or catabolic stress. Specifically, protein intakes higher than the RDA result in significantly greater gains in lean body mass during resistance training and better attenuation of lean mass loss during energy restriction.

  • supports: Protein Intake Greater than the RDA Differentially Influences Whole-Body Lean Mass Respons… (Advances in nutrition (Bethesda, Md.) 2020) · cited 40x in the literature
    "Under stressful conditions such as energy restriction (ER) and physical activity, the RDA for protein of 0.8 g · kg-1 · d-1 may no longer be an appropriate recommendation. Under catabolic or anabolic conditions, higher protein intakes are proposed to attenuate the loss or increase the gain of whole-body lean mass, respectively... In the subgroup analyses, protein intakes greater than the RDA attenuated lean mass loss after ER [0.36 (0.06, 0.67) kg, n = 14], increased lean mass after resistance training (RT) [0.77 (0.23, 1.31) kg, n = 3], but did not differentially affect changes in lean mass [0.08 (-0.59, 0.75) kg, n = 7] under nonstressed conditions (no ER + no RT)." (abstract, results, passage verified)
    pubmedfull study (doi)
2:25:00Brady Holmersupportedmoderate

Consuming protein across three to four evenly spaced meals containing 25 to 30 grams or more optimizes 24-hour muscle protein synthesis.

"based on, you know, muscle protein synthesis data that Luc van Loon um cited, it seems to be optimal to eat three to four protein-containing meals containing, you know, 25 to 30 grams or more throughout the day, evenly spaced. Um that's for optimizing muscle protein synthesis." (said at 2:25:00)

Randomized clinical trials evaluating acute and 24-hour muscle protein synthesis (MPS) confirm that distributing dietary protein evenly across 3 to 4 meals containing moderate doses (approximately 20 to 30 grams per meal) stimulates 24-hour MPS significantly more effectively than skewing intake toward a single large evening meal or consuming smaller, more frequent pulse doses.

2:14:57Rhonda Patrick (host)supportedlow

Observational research on sauna use indicates that a frequency of two sessions per week is the minimum threshold associated with reduced mortality benefits.

"And it seems as though like the minimum effective dose to get some benefits is really two times a week of sauna use." (said at 2:14:57)

Observational cohort data from Finland (the Kuopio Ischaemic Heart Disease study) evaluated sauna bathing frequency by categorizing participants into 1 session per week (reference group), 2 to 3 sessions per week, and 4 to 7 sessions per week. These prospective analyses found significant dose-dependent reductions in sudden cardiac death, fatal cardiovascular disease, and all-cause mortality starting in the group reporting 2 to 3 sessions per week compared to those using the sauna once per week. Because these findings stem from observational cohort designs, the certainty of evidence is low due to potential residual confounding.

Unverified means no publication matching the claim was located; it does not prove the claim false. Spotted an error? See the corrections policy - disputes from the people quoted are prioritized.